1. Field of the Invention
The present invention relates to a dielectric recording medium for recording information in a dielectric material or reproducing it, and a method of and an apparatus for producing the dielectric recording medium.
2. Description of the Related Art
Recently, many types of dielectric materials and piezoelectric materials have been developed, and most of them are used for ultrasonic elements, optical elements, a memory, and the like. In accordance with the fact, a method of measuring a remanent polarization distribution of the dielectric material and local anisotropy of the piezoelectric material has been developed. Also, by using this technique, another technique of recording information in the dielectric material and reproducing the information has been developed.
In order to record information in the dielectric material, a polarization direction of the polarization domain of the dielectric substance is formed such that the polarization direction corresponds to the information. For example, when using as a recording medium a ferroelectric bulk single crystal such as LiTaO3, which has 180 degree domain, the Z-cut single crystal is mechanically grinded to prepare a thin film, and then, its back surface is applied onto a conductor substrate with a conductive paste to hold. The medium as formed above is used as a dielectric recording medium.
Alternatively, after the back surface of a crystal material of the dielectric substance is applied onto the conductor substrate with the conductive paste to hold, a thin film is formed by ion beam etching or the like from the side of the front surface. The medium as formed above is also used as the dielectric recording medium.
As described above, in order to record information in the high density in a microdomain, it is necessary to form the recording medium as thin as possible, as well as making the diameter of a probe for recording and reproducing small. Therefore, the thin film is conventionally prepared by the mechanical grind, the etching with ion beam, and the like.
However, the method by the mechanical grind is limited in thinning the medium on the order of several μm, even using an oblique grinding method of grinding a crystal with its back surface inclined slightly to the surface of a grinding apparatus. It is also difficult to make it thinner while keeping a stable form because the lack of crystal strength causes fracture.
Moreover, the etching by ion beam can make the film thinner than the mechanical grind can, but it is difficult to form the recording medium in uniform thickness while ensuring the reproducibility, and it takes a long time to complete.